Failed to add a service. Service metadata may not be access

Question

Error: Cannot obtain Metadata from http://localhost:61431/RoleService.svc If this is a Windows (R) Communication Foundation service to which you have access, please check that you have enabled metadata publishing at the specified address. For help enabling metadata publishing, please refer to the MSDN documentation at http://go.microsoft.com/fwlink/?LinkId=65455.WS-Metadata Exchange Error URI: http://localhost:61431/RoleService.svc Metadata contains a reference that cannot be resolved: 'http://localhost:61431/RoleService.svc'. The content type text/html; charset=utf-8 of the response message does not match the content type of the binding (application/soap+xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 1024 bytes of the response were: '

HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

Detailed Error Information:

Module	ÿÿÿIIS Web Core
Notification	ÿÿÿUnknown
Handler	ÿÿÿNot yet determined
Error Code	ÿÿÿ0x800700b7
Config Error	ÿÿÿConfig section 'system.webServer/modules' already defined. Sections must only appear once per config file. See the help topic for exceptions
Config File	ÿÿÿ\\?\D:\CareerFramework\CG.RS.ServiceLayer\web.config

Requested URL	ÿÿÿhttp://localhost:61431/RoleService.svc
Physical Path	ÿÿÿ
Logon Method	ÿÿÿNot yet determined
Logon User	ÿÿÿNot yet determined
Request Tracing Directory	ÿÿÿD:\Users\hariskul\Documents\IISExpress\TraceLogFiles\

Config Source:

  190:       191:     192:   

More Information:

This error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error.

If you see the text "There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined", this error is because you are running a .NET Framework 3.5-based application in .NET Framework 4. If you are running WebMatrix, to resolve this problem, go to the Settings node to set the .NET Framework version to ".NET 2". You can also remove the extra sections from the web.config file.

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My web config file code

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i need proper solution